R200 DRM/KMS

[Alex Deucher]

On Mon, Jul 6, 2015 at 2:40 PM, Steven Newbury <steve at snewbury.org.uk> wrote:
> On Mon, 2015-07-06 at 12:25 -0400, Alex Deucher wrote:
>> On Mon, Jul 6, 2015 at 9:39 AM, Steven Newbury <steve at snewbury.org.uk
>> > wrote:
>> > Hi,
>> > I've been trying to get DRM/KMS working with the current graphics
>> > stack (xf86-video-ati 7.5, xserver-1.17) on a R200 series card.  I
>> > assumed this should be working since KMS was implemented for it a
>> > while back, and it has been working with xf86-video-ati-6.x.
>> >
>> > Unfortunately, it doesn't seem to work.
>> >
>> > I've narrowed it down to drmSetInterfaceVersion() failing when
>> > called
>> > from the ATI driver (in radeon_kms.c).  This is a bit strange
>> > since,
>> > /sys/class/drm/version correctly reports 1.1.0 20060810.  Presuably
>> > it's getting the correct fd for the DRM master otherwise it should
>> > bail earlier?
>> >
>> >
>> > Googling confirms others have had the same issue, and generally the
>> > resolution has been to stick with the old driver.
>> >
>> > Should this be working?  Is it known to be broken?
>>
>> It should be working.  Make sure the kernel driver has kms enabled,
>> firmware available, and that the kernel driver is loaded before
>> starting X.  If the kernel driver is not loaded before X starts you
>> can get a version mis-match error.
>
> Yes, using Gentoos 4.1.1 kernel, driver is definitely loaded, with
> modeset=1, which is working, all sysfs entries are there.  gdm manages
> to fall back to starting up an X session without using DRM swrast
> -only, not something you want to experience on such a weak CPU!
>

If the kernel driver loads properly and you get a kms console you
should be good to go.

> Manually starting X fails with the "[drm] failed to set drm interface
> version." error.
>

Maybe the ddx with that old system was build without KMS support?

Alex

> It's a very old system, PCI-only(!) Coppermine-128, belonging to a
> friend.  The system previously was (very slowly) running Ubuntu 10
> LTS, I think.  It's not my machine so I'm not able to have continuous
> access, but R200 DRM/KMS was working.  Apparently, Ubuntu no longer
> support R200, so no further updates were possible.
>
> My friend can't afford a new machine at the moment; and since I'm a
> long time Gentoo dev I took it upon myself to build him a optimized
> desktop with gcc-5, where possible LTO, -Os, -march=pentium3 with the
> system L1 and L2 cache size information.  It's quite possible some
> part of the gfx stack is miscompiled, I tested it pretty throughly
> under qemu (with qxl) before deployment, but that of course didn't
> exercise the R200 driver.  FWIW, other than the failing DRI,
> performance is surprisingly OK, not super fast obviously, but a *lot*
> better than under Ubuntu! (start-up time is alot quicker, by an order
> of magnitude!)
>
> I'm attempting to downgrade the xserver and drivers (on the live
> system) to see if that works, you can imagine that takes a little
> while on a Coppermine-128!  I'll find out tomorrow.  Otherwise, I
> guess I'm recompiling the stack with gcc-4.9 and no-LTO...